line equations

[kippylynn]

:? :? How do I get the x # in x+y=10 or y=x+10? Also I need help with like y=15/8+b. I do okay until I get to something b=9-15/8*4. How do you get y=15/8x+3/2 from that?

 

[jonboy]

You've got a lot of q's, but not a problem!

How do I get \(\displaystyle x\) in \(\displaystyle \L \;1)\,x\,+\,y\,=\,10\;&\;2)
\,y\,=\,x\,+\,10\) ?

For \(\displaystyle 1\), Subtract \(\displaystyle y\) from both sides of the equations which "balances" it because you did the same thing to both sides of the equation.

For \(\displaystyle 2\), Subtract \(\displaystyle 10\) from both sides and use Symmetric Property of Equality.

How do I get \(\displaystyle \L \;y\,=\,\frac{15}{8}x\,+\,\frac{3}{2}\) from \(\displaystyle \L \;y\,=\,\frac{15}{8}x\,+\,b\) ?

Work out what \(\displaystyle b\) is ( b=9-15/8*4) and substitute it in the slope intercept form equation with the \(\displaystyle b\) variable.

 

[kippylynn]

Thanks a lot!!!

 

[Denis]

If you can't isolate the x in x+y=10, then you're certainly not ready
for line equations; only your teacher can help you.

 

[kippylynn]

My problem is trying to find the right #'s to be able to graph two and three points that are on the have slope. Can I pick just any #'s? I'ts been awhile since I've been in school but I don't remember graphing being this complicated.

 

[Denis]

So you're studying math on your own? Good for you :idea:

"How do I get the x # in x+y=10"
So you're asking: if I let x = a number, say 4, how do I "put it" in the equation?
Very simple; replace the x with 4: 4 + y = 10
The you can solve for y:
y = 10 - 4
y = 6

So (4,6) is a graph point.